High-performance flow heater

ABSTRACT

A flow heater ( 100, 200, 300, 400, 500, 600, 700, 800 ) with a metal section ( 101, 201, 301, 401, 501, 601, 701, 801 ), with at least one tube ( 103, 104, 203, 204, 303, 304, 403, 503, 603, 604, 705, 706, 707, 708, 709, 710, 805, 806, 807, 808, 809, 810 ) for passing through a fluid to be heated is mounted and preferably pressed, at least in some sections, into the metal section ( 101, 201, 301, 401, 501, 601, 701, 801 ). At least one tubular heating body ( 102, 202, 209, 210, 302, 402, 409, 410, 502, 602, 702, 703, 704 ) that is arranged outside the tube interior space, is mounted in and preferably pressed into, the metal section ( 101, 201, 301, 401, 501, 601, 701, 801 ) at least in some sections. The at least one tubular heating body ( 102, 202, 302, 402, 502, 602, 702, 802 ) is surrounded by the one tube or by a plurality of the tubes ( 103, 104, 203, 204, 303, 304, 403, 503, 603, 604, 705, 706, 707, 708, 709, 710, 805, 806, 807, 808, 809, 810 ) for passing through a fluid to be heated. A process for manufacturing such a flow heater is also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119 ofGerman Utility Model DE 20 2010 006 739.1 filed May 12, 2010 and GermanPatent Application DE 10 2011 012 770.4 filed Mar. 1, 2011, the entirecontents of each of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention pertains to a flow heater with a metal section,with at least one tube for passing through fluid to be heated, which ismounted in and preferably pressed into the metal section at least insome sections, and with at least one tubular heating body, which isarranged outside the tube interior space and is mounted in andpreferably pressed into the metal section at least in some sections.

BACKGROUND OF THE INVENTION

Such flow heaters are used to heat fluids (i.e., especially liquidsand/or gases) and are used, for example, in dishwashers, steam cookersor washing machines and are known, for example, from DE 42 26 325 C1.

Prior-art flow heaters usually have a metal section, in which a tube forpassing through a fluid to be heated is mounted. One or more adjacenttubular heating bodies, which are likewise mounted in the metal section,are arranged around the tube outside the tube interior space thereof. Toguarantee a direct and close contact between the metal section andtubular heating body, on the one hand, and the metal section and tubefor passing through a fluid to be heated, on the other hand, thearrangement is usually fully or partly compressed.

The requirement on the performance of such flow heaters has noticeablyincreased over the last few years. It was found that the flow heaters ofconventional design, as they are known from the state of the art, reachtheir limits with the use of tubular heating bodies of ever-increasingperformance, because sufficient heat transfer into the fluid is nolonger guaranteed. This leads to an unacceptably high temperature on theoutside of the flow heater and in the extreme case to melting of themetal section.

In a second type of flow heaters, which are known, e.g., from DE 10 2005036 816 A1, a tubular heating body is arranged in the interior of a tubefor passing through a fluid to be heated. Thus, it is in direct contactwith the fluid, which significantly increases the risk of failure of thetubular heating body as a consequence of the interaction thereof withthe fluid, because local deposits, for example, calcifications, whichhinder the dissipation of heat and lead to destruction of the tubularheating body, occur in the systems used in practice in a number ofapplications. If corrosive media are heated, the direct contact with thefluid may likewise damage the tubular heating body. In addition,especially if they are used with high surface loads and low flowvelocities, such flow heaters may cause bubbling in liquids to beheated, which will likewise lead to a local hindrance of the dissipationof heat and entail the risk of destruction.

SUMMARY OF THE INVENTION

The object of the present invention is consequently to provide ahigh-performance but nevertheless compact flow heater, which can be usedin situations with limited availability of space and whose outertemperature remains limited and which ensures good heat transfer to thefluid, while the tubular heating body is at the same time protected fromthe fluid.

According to the invention, a flow heater is provided with a metalsection, with at least one tube for passing through fluid to be heated,which is mounted in and preferably pressed into the metal section atleast in some sections, and with at least one tubular heating body. Thetubular heating body is arranged outside the tube interior space and ismounted in and preferably pressed into the metal section at least insome sections. The tubular heating body is surrounded at least in somesections by one or more of the tubes for passing through a fluid to beheated.

The flow heater according to the present invention has a metal section,with at least one tube for passing through a fluid to be heated or aplurality of fluids to be heated, which is mounted, at least in somesections, in the metal section and is preferably pressed in, and atleast one, preferably pressed-in tubular heating body, which is arrangedoutside the tube interior space and is mounted at least in some sectionsin the metal section. Consequently, the tube extends adjacent to thetubular heating body, which does not absolutely require a directcontact, but it does express the fact that the tube extends separatelyfrom the tubular heating body but does so in the vicinity thereof ordirectly adjoining same.

The term “tubular heating body” is to be defined very broadly in thecontext of this patent specification; in embodying the presentinvention, it is possible to use as the tubular heating body, inprinciple, any heating element with a metal (outer) jacket, i.e., even aheating cartridge, a flat heating element or a hollow cartridge.

It is essential for the present invention that at least one tubularheating body is surrounded by a tube arrangement of at least one tube ora plurality of the tubes for passing through fluid (a fluid or fluids)to be heated at least in some sections, so that it is ensured that theheat released by the tubular heating body is released mostly into thefluid to be heated.

Consequently, an essential idea of the present invention is to abandonthe current design principle, in which it was important to maximize theintroduction of heat into the fluid by providing a tube surrounded by atubular heating body (arranged, e.g., in a coiled or meandering patternaround the tube) or by a plurality of tubular heating bodies for passingthrough a fluid to be heated, utilizing the larger outer surface of thetube for passing through a fluid to be heated. This design principleabandonment is based on the discovery that the provision of one or moretubes for passing through the fluid to be heated, whichsurrounds/surround the tubular heating body or tubular heating bodies,effectively utilizes the capacity of the tubular heating body and herebyprevents excessive heating of the outer surface of the metal sectionalong with a simultaneous good heating capacity.

It is pointed out for clarification that the terms “surround” and“enclose” are to be clearly distinguished within the framework of thepresent invention. “Surround” means that when viewed at right angles tothe direction in which the surrounded tubular heating body extends,sections of one or more tubes for passing through a fluid to be heatedare arranged in a plurality of directions, which especially also formangles exceeding 90° relative to one another. Only the term “surround”is used in the sense that when viewed at right angles to the directionin which the surrounded tubular heating body extends, sections of one ormore tubes for passing through a fluid to be heated are arranged in alldirections.

In an advantageous embodiment of the present invention, the metalsection is a hollow section or it forms a component of a compositehollow section. A hollow section is present if a hollow space is definedby the metal section, optionally in conjunction with additional wallsections, which may be formed, for example, by wall sections of a tubefor passing through a fluid to be heated. A hollow section may be, inprinciple, open or closed. An example of an open hollow section is atube; if the openings of the tube are closed with covers, an example ofa closed hollow section is obtained.

The tubular heating body and the tube arrangement with the at least onetube for passing through a fluid to be heated are arranged andpreferably pressed in at least in some sections in the hollow section,i.e., in the interior of the hollow space, together with a sealingcompound or with a powder or granular material, in which the heater, theat least one tube for passing through a fluid to be heated or the heaterand the at least one tube for passing through a fluid to be heated areembedded at least partly.

By providing a hollow section, in which the heater and/or the at leastone tube for passing through a fluid to be heated are arranged togetherwith a powder or granular material, in which the heater and the at leastone tube for passing through a fluid to be heated are embedded at leastpartly, and are preferably pressed in at least in some sections, itbecomes unnecessary to prepare grooves or holes in the metal section,because the thermal contact is established via the powder or granularmaterial, which not only saves costs and ensures a more reliable thermalcontact, but also permits a more flexible shaping of the heater andtubes, because the sealing compound or the powder or granular materialcan be filled in later. It becomes possible, for example, to use tubesor heaters with a one-sided connection, which makes possible a morecompact installation.

An especially simple and cost-effective flow heater is obtained if thehollow section comprises two metal sections connected to one another.This makes it possible to simply provide a metal section as a bottom, toinsert the heater and tubes in said bottom and then to attach anothermetal section as a cover, which is then connected to the bottom, forexample, by soldering or welding. If the cover and bottom form an openhollow section, the “profiled tube” formed may be filled with powder ora granular material, e.g., in a forging die, optionally compacted andoptionally provided with front-side closing surfaces. A closed hollowsection is formed if the cover and/or bottom have side walls each, whichdefine a closed space in the connected state when the heater and tubesare inserted, and the powder or granular material must be inserted inthis case before the cover and bottom are connected to one another.

An especially compact design of the flow heater is obtained by thehollow section being composite and by at least one section of the wallof the at least one tube for passing through a fluid to be heatedforming, besides the at least one metal section, a component of thecomposite hollow section, because this avoids a complete “buildingaround” the tubes. Especially simple here is a design in which at leasttwo tubes for passing through a fluid to be heated are present and thehollow section is formed from sections of the walls of the tubes forpassing through a fluid to be heated and metal sections, which connectthese sections of the wall of the tubes. The simplest design thus formedwould be an open hollow section, i.e., one formed from a cover formed bya metal section and a bottom formed by a metal section.

It is especially preferred because of this good heat conduction that canthus be achieved if the powder or granular material consists of metal,especially aluminum, copper, brass or a mixture thereof.

In an advantageous embodiment, at least one tube for passing through afluid to be heated is directly in contact at least in some sections withthe heater in the form of the tubular heating body, which makes possiblean especially direct heat transport. In particular, a tube can extend,led around a tubular heating body, such that the tube surrounds thetubular heating body on all sides, for example, if a tube coiled aroundthe tubular heating body is used.

Another advantageous embodiment of the flow heater is characterized inthat the metal section consists of a material that has a poorer thermalconductivity than the powder or granular material. As a result, thetemperature prevailing on the surface of the flow heater at a givenpower consumption of the flow heater can be markedly reduced at equaloutside dimensions compared to prior-art flow heaters, in which the heattransport takes place from the heater to the tube via the metal section,which must therefore be manufactured from a material with good thermalconductivity, and the use of metal sections with poor conductivity,e.g., those made of Cr—Ni steel, is made possible. In addition, thematerial costs for the metal sections can thus be reduced.

A control and/or regulating element is advantageously provided at theflow heater. Manufacturing losses are avoided in case ofpressure-sensitive control and/or regulating elements if the controland/or regulating element is arranged on the outside of the metalsection. Embedding of the control and/or regulating element in thepowder or granular material makes regulation possible on the basis ofdata that are detected with very high accuracy close to the site of heattransfer. In embodiments without the use of powder or granular material,this effect can also be achieved if the measuring and/or regulatingelement is embedded at a suitable point of the metal section or of themetal jacket of the tubular heating body.

The measuring and/or regulating element is preferably connected inseries with at least one resistance wire winding of the tubular heatingbody in order to guarantee fast response times.

Another advantageous variant of the present invention makes provisionsfor at least one tube for passing through a fluid to be heated to havecross sections varying in contour in the direction in which it extends.Provisions are made in an advantageous variant for selectingcrescent-shaped tube cross sections in the middle area, which makes goodadaptation to the geometry of the tubular heating body possible, and forpassing over in the end areas of the tubes to round cross sections,which can be connected especially easily. This possibility was notavailable until now due to the necessity of providing a groove or hole,into which the heater had to be inserted, and this led to an appreciablelimitation of the design parameters for the flow heater. In particular,the present invention makes it possible for at least one tube forpassing through a fluid to be heated to be shaped such that it can bepushed over the heater, but good transfer of the heat from the areas ofthe heater at which the tube is not directly in contact to the tube canbe ensured at the same time via the powder or granular material. Theheater can be operated with a higher output because of the heatdissipation thus improved.

The process according to the present invention for manufacturing such aflow heater comprises the following steps:

-   -   Providing a one-piece hollow section designed as a metal section        or composed of a plurality of components, containing at least        one metal section, with a heater arranged at least in some        sections in the interior space of the hollow section and at        least one tube for passing through a fluid to be heated, which        is arranged at least in some sections in the interior space of        the hollow section;    -   Filling at least part of the interior space of the hollow        section with a sealing compound, a powder or granular material;        and preferably pressing in, at least in some sections, of the        heater and of the at least one tube into the hollow section.

It should be borne in mind, in particular, that depending on how thehollow section is designed, the step of filling may be carried out afterproviding the hollow section or it may be integrated in the providingstep.

Structuring of the metal section, which was hitherto necessary, can beavoided due to this process just as completely as the laboriousinsertion of the heater and tubes for passing through a fluid to beheated, which leads to an especially simple and cost-effectivemanufacture with more degrees of freedom in design.

In a preferred embodiment of the process, a metal section is madeavailable as a bottom element for providing a hollow section composed ofa plurality of components containing at least one metal section. Theheater and the at least one tube for passing through a fluid to beheated are arranged on or at the bottom element. This may also becarried out, for example, in fitted openings of the bottom element,which brings about an especially reproducible arrangement of theelements of the flow heater relative to one another.

In the further course of the process, the metal section provided in thisembodiment as a bottom element is connected to at least one additionalmetal section, especially a cover element and/or at least one section ofthe wall of a tube for passing through a fluid to be heated in order toprovide the hollow section. The filling of at least part of the interiorspace of the hollow section is preferably performed in this procedurebefore all the components of the hollow section are completely connectedto one another.

An alternative advantageous embodiment of the metal section is obtainedif the metal section is a tensioning mechanism for generating apressure, which brings about the pressing into the metal section. Themetal section may optionally additionally ensure the holding together ofthe tubular heating body and tubes. Flow heaters of this embodiment areespecially compact and can be manufactured in a cost-effective manner.Another advantage of this embodiment is that very strong pressing-inpressures can be permanently applied, which leads to an especiallyintimate thermal contact of the components of the flow heater and thuspermits good heat transmission. Tightening straps, tensioning clips orpreformed, pressed sections are especially suitable for use astensioning mechanisms. However, it is also possible to provide atensioning mechanism by soldering or welding the tubes in the compressedstate, after which the metal section can be seen in the soldered jointsand/or weld seams.

Another, especially robust, alternative embodiment of the metal sectionis obtained if the metal section is a massive body, especially analuminum or brass body, in which the pipe and tubular heating body aremounted and embedded, preferably pressed in. To facilitate the assemblyof such an arrangement, holes may be provided in the metal section. Inparticular, it is also possible that the holes for the tubular heatingbody and tubes for passing through a fluid to be heated pass over intoeach other, so that the metal section forms the “frame” for theserecesses. This facilitates the assembly of the flow heater.

The shape of the wall of at least one of the tubes for passing through afluid to be heated, which said tubes surround the at least one tubularheating body, or of the tube for passing through a fluid to be heated,which said tube surrounds the tubular heating body, wherein said wallfaces the tubular heating body, is adapted in an especially advantageousembodiment to a section of the surface of the tubular heating body.Especially good and homogeneous heat transfer is guaranteed hereby.

An adaptation in the sense of the present invention is already presentif the same geometric shape is present, especially if the surfacesections adapted to one another extend at constant distance from eachother; there do not need to be mutually covering fitting surfaces. Forexample, surface segments of two concentric, cylindrical jacket surfaceswith markedly different radii are thus fitted surface sections in thesense of the present invention.

It is advantageous, furthermore, if the shape of the wall of at leastone of the tubes surrounding the at least one tubular heating body or ofthe tube surrounding the tubular heating body, which said wall facesaway from the tubular heating body, is adapted to a section of thesurface of the metal section facing away from the surrounding tubularheating body. This entails an especially homogeneous heat distributionon the surface of the flow heater.

If a metal section is provided, which has at least one web, via whichthe surface of the metal section, which said surface faces away from thetubular heating body, is connected to the tubular heating body, theadvantage is gained that regulating and securing elements arranged onthe outside of the flow heater can respond and effectively preventoverheating or even melting of the metal section. It is especiallyfavorable if at least two tubes for passing through a fluid to be heatedare provided, which overlap each other, when viewed from the surroundingtubular heating body in a direction at right angles to the direction inwhich it extends, at least in some sections, because homogeneous heatdistribution is thus brought about on the surface of the flow heater.

An alternative advantageous embodiment of the flow heater makesprovisions for a tube for passing through the fluid to be heated toenclose at least one tubular heating body. This leads to an especiallyhomogeneous heat distribution, but is associated with a greater designeffort.

An especially efficient heat transfer can be achieved in a situation inwhich the requirements of the space available for installation requirean especially compact design if at least one of the tubes for passingthrough a fluid to be heated, which said tubes surround the at least onetubular heating body, is directly in contact with the surrounded tubularheating body.

If the smallest possible design is not absolutely necessary, a heattransport tube may be arranged on the tubular heating body. The size ofthe heated tube inner surface can thus be varied. This measure createsan additional degree of freedom for coordination between the desiredfluid throughput and the needed heat output at a given length of theflow heater. Moreover, the thermal contact between the tubular heatingbody and tube for passing through a fluid to be heated can be improvedby selecting a material with higher elasticity and/or lower hardnessand/or better deformability compared to the material of the metal jacketof the tubular heating body, especially if the material of the heattransport tube has a higher thermal conductivity than the material ofthe metal jacket of the tubular heating body.

Provisions are made in an alternative variant of the flow heater tothis, which is especially favorable in terms of manufacturingtechnology, for the tubular heating body being mounted in a hole in themetal section. Especially cost-effective flow heaters are obtained ifthe at least one tube for passing through a fluid to be heated is adrawn special section tube.

Especially good connection possibilities are obtained for the flowheater if adapter pieces are provided on at least one of the tubes forpassing through a fluid to be heated.

Especially high safety against failure is achieved with a flow heater inwhich the tubular heating body is essentially unheated in the sectionsin which it can come into direct contact with the fluid to be heated,especially in sections which are not mounted in, preferably not pressedinto, the metal section. This can be achieved, e.g., by means of areasin which the resistance wire is not arranged in a coiled or meanderingpattern or is led through these areas over as direct a route aspossible. Damage to the tubular heating body, which may be possible dueto the contact with the fluid, and leads to the failure thereof, isthereby. For example, heat dissipation from the tubular heating body maybe locally hindered in case of water due to the buildup of a layer oflime, which may lead to overheating and failure of the tubular heatingbody.

Another, especially advantageous form of the flow heater has a tubearrangement with at least two tubes for passing through fluid to beheated, which are intended to be connected to different fluid circuits.The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference is made to the accompanying drawings and descriptive matter inwhich preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of a first exemplary embodiment of thepresent invention;

FIG. 1 a is a sectional view along line A-A of the exemplary embodimentfrom FIG. 1;

FIG. 1 b is a sectional view along line B-B of the exemplary embodimentfrom FIG. 1;

FIG. 2 is a perspective view of a second exemplary embodiment of thepresent invention;

FIG. 2 a is a sectional view along line A-A of the exemplary embodimentfrom FIG. 2;

FIG. 2 b is a sectional view along line B-B of the exemplary embodimentfrom FIG. 2;

FIG. 3 is a sectional view of a third exemplary embodiment of thepresent invention, corresponding to the section in FIG. 1 b;

FIG. 4 is a sectional view of a fourth exemplary embodiment of thepresent invention, corresponding to the section in FIG. 2 b;

FIG. 5 is a sectional view of a fifth exemplary embodiment of thepresent invention, corresponding to the section in FIG. 1 b;

FIG. 6 is a sectional view of a sixth exemplary embodiment of thepresent invention, corresponding to the section in FIG. 1 b;

FIG. 7 is a perspective view of a seventh exemplary embodiment of thepresent invention;

FIG. 7 a is a sectional view along line B-B of the exemplary embodimentfrom FIG. 7;

FIG. 8 is a perspective view of an eighth exemplary embodiment of thepresent invention;

FIG. 8 a is a sectional view along line A-A of the exemplary embodimentfrom FIG. 8;

FIG. 8 b is a sectional view along line B-B of the exemplary embodimentfrom FIG. 8;

FIG. 9 a is a perspective view of a ninth exemplary embodiment of thepresent invention;

FIG. 9 b is a cross section of the exemplary embodiment from FIG. 9 a;

FIG. 10 a is a perspective view of a tenth exemplary embodiment of thepresent invention;

FIG. 10 b is a cross sectional view through the exemplary embodimentfrom FIG. 10 a;

FIG. 11 a is a perspective view of an eleventh exemplary embodiment ofthe present invention;

FIG. 11 b is a partially sectional view showing the interior of theexemplary embodiment from FIG. 11 a;

FIG. 12 a is a perspective view showing a twelfth exemplary embodimentof the present invention;

FIG. 12 b is a perspective view showing the components of the exemplaryembodiment from FIG. 2 a before assembly;

FIG. 12 c is a sectional view along line B-B of the exemplary embodimentfrom FIG. 12 a;

FIG. 13 a is a perspective view of a thirteenth exemplary embodiment ofthe present invention;

FIG. 13 b is a perspective view showing the components of the exemplaryembodiment from FIG. 13 a before assembly;

FIG. 13 c is a sectional view along line B-B of the exemplary embodimentfrom FIG. 13 a;

FIG. 14 a is a perspective view of a fourteenth exemplary embodiment ofthe present invention;

FIG. 14 b is a cross sectional view through the exemplary embodimentfrom FIG. 14 a along line A-A; and

FIG. 14 c is a cross sectional view along line A-A in a variant of theexemplary embodiment from FIG. 14 a.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in particular, identical reference numbers areused in all figures for identical components of the same exemplaryembodiments.

FIG. 1 shows a flow heater 100 according to the present invention with ametal section 101 designed as a solid body, with a tubular heating body102, which passes through the metal section 101 and is mounted andembedded and preferably pressed into the metal section 101 at least insome sections, and with a tube arrangement comprising two tubes 103, 104for passing through a fluid to be heated, which pass through the metalsection 101 and are mounted and preferably pressed into the metalsection 101 in some sections. Adapter pieces 104, 105, 106, 107 arearranged at the ends of the tubes 103, 104 for passing through a fluidto be heated.

Based on the cross-sectional view shown in FIG. 1 a along line A-A, thecourse of the tubular heating body 102 and of the tubes 103, 104 forpassing through a fluid to be heated as well as the embedding thereof inthe metal section 101 are seen especially clearly.

The section shown in FIG. 1 b along line B-B shows especially clearlyhow the tubes 103, 104 for passing through a fluid to be heated surroundthe tubular heating body 102. This view shows the plane at right anglesto the direction in which the tubular heating body 102 extends.Beginning from the tubular heating body 102, a section each of a tube103, 104 for passing through a fluid to be heated is arranged in aplurality of directions between the tubular heating body 102 and thesurface of the metal section 101, which surface faces away from thetubular heating body. The tubes 103, 104 thus surround the tubularheating body 102 in the sense of the present invention. However, thetubular heating body 102 is not enclosed, because webs 111, 112 connectthe surface of the metal section 101 facing away from the tubularheating body 102 to the tubular heating body 102 in two directions.

Furthermore, FIG. 1 b shows that in the tubes 103, 104, the wall facingthe tubular heating body 102 or wall section 114, 113 facing saidtubular heating body extends at a constant distance from a section ofthe surface of the tubular heating body 102. The wall sections 114, 113are therefore adapted to the corresponding section of the surface of thetubular heating body 102.

Furthermore, this view shows as an example a typical inner structure ofthe tubular heating body 102, which is known per se, which has here, forexample, within a metal section, a coil of a heat conductor embedded inan insulating material or a resistance wire.

FIGS. 2, 2 a and 2 b show a second embodiment of the present inventionwith a flow heater 200, a metal section 201, tubular heating bodies 202,209, 210 a tube arrangement with tubes 203, 204, adapter pieces 205,206, 207, 208 and webs 211, 212. Walls facing the tubular heating bodyare designated 213 and 214. The second embodiment differs from the viewin FIGS. 1, 1 a and 1 b only in that the two additional tubular heatingbodies 209, 210 are provided outside the tubes 203, 204. The additionaltubular heating bodies 209, 210 can bring about an increase in theheating output of the flow heater 200 compared to flow heater 100.However, their output is limited, because they are not surrounded bytubes for passing through a fluid to be heated and may thus lead to anundesired heating of the surface of the flow heater 200. Because of thevery good utilization and dissipation of the output of the centraltubular heating body 202 by the tubes 203, 204 surrounding these, it isstill possible to provide a limited additional heating output thanks tothe present invention.

FIG. 3 shows a cross section as in FIG. 1 b through a third embodimentof the present invention with a flow heater 300, a metal section 301, atubular heating body 302, a tube arrangement with tubes 303, 304 andwebs 311, 312. Walls facing the tubular heating body are designated 313and 314. The third embodiment differs from the view in FIGS. 1, 1 a and1 b only by the shape of the tubes 303, 304 for passing through a fluidto be heated. The embodiment according to FIG. 3 has tubes, whoserespective wall 315, 316 facing away from the tubular heating body 302is adapted to a section of the surface of the metal section 301, whichsaid surface faces away from the tubular heating body 302.

FIG. 4 shows a cross section as in FIG. 2 b through a fourth embodimentof the present invention with a flow heater 400, a metal section 401,tubular heating bodies 402, 409, 410 a tube arrangement with only onetube 403 and web 411. A wall facing the tubular heating body isdesignated 413. The fourth embodiment differs from the view in FIGS. 2,2 a and 2 b only in that the surrounding, according to the presentinvention, of a tubular heating body 402 is achieved only by means of atube 403, which is placed nearly completely around the tubular heatingbody 402, but a web 411 still continues to connect the surface of themetal section 401, which said surface faces away from the tubularheating body 402, to the tubular heating body 402.

FIG. 5 shows a cross section as in FIG. 1 b through a fifth embodimentof the present invention with a flow heater 500, a metal section 501, atubular heating body 502, a tube arrangement with tubes 503, 504 andwebs 511, 512. Walls facing the tubular heating body are designated 513and 514. The fifth embodiment differs from the view in FIGS. 1, 1 a and1 b only by the shape of the tubes 503, 504 for passing through a fluidto be heated. The embodiment according to FIG. 5 has tubes 503, 504 forpassing through a fluid to be heated, which not only surround the heatconductor 502—this would be achieved by the tube 503 alone—but togetherenclose it. Viewed from the surrounded tubular heating body 502,sections of the tubes 503, 504 for passing through a fluid to be heatedare arranged in all directions at right angles to the direction in whichthe surrounded tubular heating body 502 extends. However, webs 511, 512are still present, which connect the surface of the metal section 501,which surface faces away from the tubular heating body 502, to thetubular heating body 502. Thus, monitoring of the temperature of themetal section 501 in the interior thereof continues to be possible.

FIG. 6 shows a cross section as in FIG. 1 b through a sixth embodimentof the present invention with a flow heater 600, a metal section 601, atubular heating body 602, a tube arrangement with tubes 603, 604 andwebs 611, 612. Walls facing the tubular heating body are designated 613and 614. The sixth embodiment differs from the view in FIGS. 1, 1 a and1 b slightly by the shape, but mainly by the arrangement of the tubes603, 604 for passing through a fluid to be heated. The embodimentaccording to FIG. 6 has tubes 603, 604, whose respective wall 614, 613facing the tubular heating body 602 is not only adapted to a section ofthe tubular heating body 602, but is in direct contact with same, whichleads to an especially direct heat transfer to the fluid to be heated.

FIG. 7 shows a flow heater 700 according to the present invention with ametal section 701 and three tubular heating bodies 702, 703, 704, whichpass through the metal section 701 and are mounted in and preferablypressed into the metal section 701 in some sections, and with a tubearrangement comprising six tubes 705, 706, 707, 708, 709, 710 forpassing through a fluid to be heated, which pass through the metalsection 701 and are mounted and especially pressed into the metalsection 701 in some sections. Adapter pieces 711, 712, 713, 714 arearranged at the ends of the tubes 705, 706, 707, 708, 709, 710 forpassing through a fluid to be heated. The adapter pieces 711, 712, 713,714 are designed in this case such that when one of their ends isconnected to a fluid supply, not shown here, a connection of three tubeends with the fluid supply is established via their other end by meansof the adapter piece 711, 712, 713, 714, which makes possible anespecially simple connection of the flow heater 700.

The section shown in FIG. 7 a along line B-B shows especially clearlyhow the tubes 705, 706, 707, 708, 709, 710 for passing through a fluidto be heated surround the tubular heating body 702. This view shows theplane at right angles to the direction in which the tubular heating body702 extends. Beginning from the tubular heating body 702, a section eachof one of the tubes 705, 706, 707, 708, 709, 710 for passing through afluid to be heated is arranged, namely, centrically symmetrically to thecenter of the cross section through the tubular heating body 702, in aplurality of directions between the tubular heating body 702 and thesurface of the metal section 701, which said surface faces away from thetubular heating body. The radial distance between the tubes 705, 706,707, 708, 709, 710 is equal.

Thus, the tubes 705, 706, 707, 708, 709, 710 surround the tubularheating body 702 in the sense of the present invention. However, thetubular heating body 702 is obviously not enclosed here, either, becausea web 715, 716, 717, 718, 719 720 each of the metal section is presentbetween two adjacent tubes.

The additional tubular heating bodies 703, 704 can bring about anincrease in the heat output of the flow heater 700 compared to the flowheater 100. However, the output of the additional tubular heating bodies703, 704 is limited, because they are not surrounded by tubes forpassing through a fluid to be heated and may thus lead to an undesiredheating of the surface of the flow heater 700. It is still possible toprovide a limited additional heat output thanks to the present inventionbecause of the very good utilization and dissipation of the output ofthe central tubular heating body 702 by the tubes 705, 706, 707, 708,709, 710 surrounding said tubular heating body.

FIG. 8 shows a flow heater 800 according to the present invention with ametal section 801, with a tubular heating body 802, which passes throughthe metal section 801 and is mounted and especially pressed into themetal section 801 in some sections, and, as can be seen only on thebasis of FIG. 8 b, with six tubes 805, 806, 807, 808, 809, 810 forpassing through a fluid to be heated, which pass through the metalsection 801 and are mounted in and especially pressed into the metalsection 801 in some sections. Respective adapter pieces 803 and 804,through which the tubular heating body 802 passes, are arranged at therespective first and second ends of the tubes 805, 806, 807, 808, 809,810 for passing through a fluid to be heated. It is essential in thisconnection that the tubular heating body 802 has, in the areas in whichit is passed through the adapter pieces 803, 804, essentially unheatedareas, in which the resistance wire, in particular, is not arranged in acoiled or meandering pattern. Damage to the tubular heating body, whichmay be possible due to contact with the fluid and leads to the failurethereof, is avoided hereby. For example, heat dissipation from thetubular heating body may be locally hindered in case of water due to thebuildup of a layer of lime, which may lead to overheating and failure ofthe tubular heating body. All sections of the tubular heating body,which are not mounted in the metal section 801, are essentially unheatedin an especially preferred embodiment of the flow heater.

It is seen especially clearly from the cross-sectional view shown inFIG. 8 a along line A-A that the adapter pieces 803, 804 are inconnection with all tubes 805, 806, 807, 808, 809, 810 for passingthrough a fluid to be heated. This is especially favorable in terms ofconnection technology and permits the use of large cross sections in thefeed areas 803 a, 804 a of the adapter pieces 803, 804. In addition,this contributes to a more uniform flow through the tubes 805, 806, 807,808, 809, 810 for passing through a fluid to be heated. The adapterpieces 803, 804 are directly in contact with the metal section 801 inthe exemplary embodiment according to FIG. 8, which leads to anespecially compact design, but an arrangement, not shown, in which theyare arranged at spaced locations from the metal section 801, is possibleas well.

Furthermore, the course of the tubular heating body 802 and of the tubes805, 806, 807, 808, 809, 810 for passing through a fluid to be heated aswell as the embedding thereof in the metal section 801 are seen.

The section shown in FIG. 8 b along line B-B shows especially clearlyhow the tubes 805, 806, 807, 808, 809, 810 for passing through a fluidto be heated surround the tubular heating body 802. This view shows theplane at right angles to the direction in which the tubular heating body802 extends. Beginning from the tubular heating body 802, a section eachof one of the tubes 805, 806, 807, 808, 809, 810 for passing through afluid to be heated is arranged in a plurality of directions between thetubular heating body 802 and the surface of the metal section 801, whichsaid surface faces away from the tubular heating body. Thus, theysurround the tubular heating body 802 in the sense of the presentinvention. However, the tubular heating body 802 is not enclosed,because webs 811, 812, 813, 814, 815, 816 connect the surface of themetal section 801, which the surface faces away from the tubular heatingbody 802, to the tubular heating body 802.

Furthermore, this view shows as an example a typical inner structure ofthe tubular heating body 802, which is known per se, which has here, forexample, within a metal section, a coil of a heat conductor embedded inan insulating material or a resistance wire.

FIG. 9 a shows a flow heater 900, which has a tube arrangementcomprising two tubes 905, 906 for passing through a fluid to be heated,which are arranged such that they surround a tubular heating body 903.As can be seen especially clearly from FIG. 9 b, the sections of thewalls of the tubes 905, 906, which said sections face the tubularheating body 903, are adapted to the shape of the tubular heating body903 and are in direct contact with the surface thereof.

Furthermore, metal sections 901 in the form of tensioning mechanisms areseen at three points of the flow heater 900, but it is also possible touse more or fewer such points as needed. These tensioning mechanismsbring about the pressing in of tubes 905, 906 and tubular heating body903 in the metal sections 901.

This embodiment of the present invention is characterized, on the onehand, by an especially compact design and a very cost-effectivemanufacture, and, on the other hand, it also permanently ensures anintimate thermal contact, because the pressing-in pressure iscontinuously maintained by the metal sections 901.

The tenth exemplary embodiment of the present invention, which is shownin FIGS. 10 a and 10 b comprises a flow heater 1000, a metal section1001, a tubular heating body 1002, a tube arrangement with tubes 1005,1006. The tenth exemplary embodiment differs from the embodimentaccording to FIGS. 9 a and 9 b, to the description of which reference ismade in view of the identical features, only in that, as can be seenespecially clearly from FIG. 10 b, an additional jacket tube is pushedin the tenth exemplary embodiment as a heat transport tube 1017 over thetubular heating body 1002, so that the thermal contact between the tubes1005, 1006 and the tubular heating body 1002 is indirect, taking placevia the heat transport tube 1017. This measure creates an additionaldegree of freedom for coordination between the desired fluid throughputand the needed heat output at a given length of the flow heater 1000, sothat the size of the heated tube inner surface can be varied. Moreover,the thermal contact between the tubular heating body 1002 and the tubes1002, 1003 for passing through a fluid to be heated can be improved byselecting a material with higher elasticity and/or lower hardness and/orbetter deformability compared to the material of the metal jacket of thetubular heating body 1002, especially if the material of the heattransport tube 1017 has a higher thermal conductivity than the materialof the metal jacket of the tubular heating body.

Prefixing of the components relative to one another, e.g., by a solderedconnection or another connection, may be optionally carried out in theembodiments shown in FIGS. 9 a, 9 b, 10 a and 10 b. However, the metalsection is essential for ensuring the needed pressing-in pressure, whichis essential for achieving the desired intimate thermal contact betweenthe tubular heating body and tube.

FIG. 11 a shows an eleventh exemplary embodiment of a flow heater 1100.A hollow section 1101 made of metal, which is designed as a cylindricaltube, is seen. End sections of a tube 1102 for passing through a fluidto be heated project from the wall of the hollow section 1101. A heater1103 in the form of a tubular heating body has electric terminals 1104,1105, which project on the front side, which are not shown in the viewof the other embodiments for reasons of clarity, and are arrangedconcentrically in the cylindrical tube 1101. The inner volume of thehollow section 1101, which is not filled out by the heater 1103 and tube1102 for passing through a fluid to be heated, is filled with a powderor granular material 1106, but this cannot be seen in FIG. 11 a, becauseit is covered by the hollow section 1101 and a front-side closing plate1107.

FIG. 11 b shows a view into the interior of the exemplary embodimentfrom FIG. 11 a, which is seen when cutting open the hollow section 1101along a diameter of the cross-sectional area, removing the part facingthe viewer and removing the powder or granular material 1106 up to thecut surface. Thus, this is not, in particular, a cross-sectional view,because neither the tube 1102 for passing through a fluid to be heatednor the heater 1103 are shown in sectional views. It is clearly seen inFIG. 11 b that the tube 1102 for passing through a fluid to be heated iswound around the heater 1103 in coils such that the two ends of the tubeare arranged at the same end of the flow heater 1100. Any other desiredshape of the tube 1102 for passing through a fluid to be heated ispossible, in principle, e.g., it may be wound in a meandering pattern ordesigned such that the two ends of the tube are arranged at differentends of the flow heater 1100. The powder or granular material may becomeself-supporting due to compaction, so that the front-side closing plates1107, 1108 optionally provided on the front sides of the flow heater1100 in this exemplary embodiment are not absolutely necessary.

The considerable advantages of the manufacture according to the presentinvention of the flow heater can also be easily illustrated on the basisof the view in FIG. 11 b. It was always necessary in hitherto ordinaryflow heaters to ensure good thermal contact between the heater 1103 andtube 1102 for passing through a fluid to be heated by high-precisionmanufacture and/or by pressing in strongly. This applied especially toembodiments in which the shape of the tube 1102 for passing through afluid to be heated prevents insertion into a groove of an extrudedsection, as this is the case in the example shown in FIG. 11 b, becausethe heat transfer must now be guaranteed completely by the directcontact between the heater 1103 and tube 1102, which cannot beguaranteed solely by simply attaching the tube 1102 for passing througha fluid to be heated to the heater 1003.

By contrast, only the hollow section 1101, tube 1102 and heater 1103must be provided to manufacture the flow heater shown in FIGS. 11 a and11 b, where the heater 1103 and tube 1102 are arranged at least in somesections in the interior space of the hollow section 1101, which isachieved by these components being either first attached to each otherand then inserted into the interior space of the hollow section 1101 orby one of the components being arranged first in the interior of thehollow section 1101 and the second being then attached.

The filling of at least part of the interior space of the hollow section1101 with a powder or granular material 1106 may subsequently takeplace, for example, in a forging die, and the heater 1101 and/or the atleast one tube is then advantageously optionally mounted and preferablypressed into this.

Good thermal contact is ensured with this procedure by the powder orgranular material 1106 even at points where inaccuracies due to themanufacturing technology or even the clearance necessary for pushing thetube 1102 over the heater 1103 have hitherto impaired this contact.

FIG. 12 a shows a view of a twelfth exemplary embodiment of a flowheater 1200 according to the present invention with a hollow section1201, whose cross section is essentially rectangular. Two tubes 1202,1204 for passing through a fluid to be heated, which are mounted atleast in some sections in the inner volume of the hollow section, areprovided in this exemplary embodiment. A heater 1203, which is designedas a tubular heating body, is arranged between the tubes 1202, 1204 forpassing through a fluid to be heated. Two optional measuring orregulating elements 1207, 1208, which monitor the flow heater 1200during operation and collect data for regulating same and/or convertthose data into control commands, with which, e.g., the flow velocity ofthe fluid or heat output, which is made available by the heater 1203,can be regulated, are provided on the outside of the hollow section.

As can be seen especially clearly from the sectional view along line B-Baccording to FIG. 2 c, the tubes 1202, 1204 for passing through a fluidto be heated and the heater 1203 are embedded in a powder or granularmaterial in the area in which they extend within the hollow section1201, as a result of which good thermal contact is ensured. It can alsobe seen especially clearly in FIG. 2 c that the tubes 1202, 1204 forpassing through a fluid to be heated have wall sections 1202 a, 1204 a,whose shape is adapted to the shape of the wall section of the heater1203 located closest, as a result of which an especially good heattransfer can be ensured.

FIG. 12 b shows the components of the exemplary embodiment from FIG. 12a before assembly. As a consequence of the embedding of the tubes 1202,1204 and of the heater 1203 in a powder or granular material, the tubes1202, 1204 for passing through a fluid to be heated can be inserted withthe desired section into the hollow section 1201 in a simple manner andheater 1203 can then be placed between the tubes 1202, 1204, even thoughthe shape of the tubes 1202, 1204 itself is such that direct insertioninto a groove of an extruded section, as is known from the state of theart, would not be possible. The assembly unit thus provided can thenwith filled with a powder or granular material, optionally preferablycompacted and, if desired, optionally closed with front-side closingplates, not shown.

FIG. 13 a shows a view of another exemplary embodiment of the presentinvention. A flow heater 1300 with two tubes 1302, 1304 for passingthrough a fluid to be heated and with a heater 1303 are seen. One of twometal sections 1301, 1305, which are connected to wall sections of thetubes 1302, 1304 and represent components of a hollow section formedtogether with these wall sections, can be seen in the view in FIG. 13 a.

As can be seen especially clearly in the sectional view according toFIG. 13 c, the inner volume of the flow heater, which is defined by themetal sections 1302, 1305 and the wall sections 1302 a, 1304 a of thetubes 1302, 1304 for passing through a fluid to be heated, is filledwith a powder or granular material 1306, in which, when viewed in thecross section, the tubes 1302, 1304 are thus partly embedded and inwhich heater 1303 is completely embedded. As described above inconnection with FIG. 12 c, wall sections of the tubes 1302, 1304 areadapted to the outer contour of heater 1303.

FIG. 13 b shows the components of the exemplary embodiment from FIG. 13a before assembly. The hollow section is provided in this case by thetubes 1302, 1304 being fastened to one of the metal sections 1301, 1305.Front-side closing plates 1307, 1308 are fastened to the same metalsection 1302, 1305 before or after the heater 1303 was pushed in betweenthem. The inner volume can then be filled with a powder or granularmaterial before fastening the second metal section 1305, 1301 and anoptional compaction may be subsequently carried out.

FIG. 14 a shows an exemplary embodiment of the present invention, whichdiffers from the design according to FIGS. 10 a and 10 b only in thatthe tensioning means are formed here by tensioned metal sections 1401,1401 a rather than being arranged only locally, as can be seen in FIG.10 a, but they extend essentially over the entire effective length ofthe flow heater, as is shown in FIG. 14 a.

The two variants of this embodiment, which are shown in FIGS. 14 b and14 c, differ in that the space between the tips of the crescents remainsfree between the tubes 1402, 1404 with crescent-shaped cross section inthe embodiment according to FIG. 14 b, so that, for example, a measuringand/or regulating element, e.g., in the form of a thermocouple, can beprovided there, whereas the variant according to FIG. 14 c hasprojections of the metal section 1401 a at these points, which leads toa more homogeneous dissipation of heat.

In all embodiments, which have more than one tube for passing through afluid to be heated, different fluid circuits can be supplied with thedifferent tubes. The possibility of providing different amounts of fluidwith a flow heater, which is made possible by the design according tothe present invention, is pointed out in this connection, in particular.

Features that can be found only in some of the embodiments can becombined with the other embodiments shown unless they contradictfeatures of these embodiments.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

LIST OF REFERENCE NUMBERS

-   A-A Section line-   B-B Section line-   100, 200, 300, 400, 500, 600, 700, 800 Flow heater-   101, 201, 301, 401, 501, 601, 701, 801 Metal section-   102, 202, 209, 210, 302, 402, 409, 410, 502, 602, 702, 703, 704,    802, 902, 1002 Tubular heating body-   103, 104, 203, 204, 303, 304, 403, 503, 603, 604, 705, 706, 707,    708, 709, 710, 805, 806, 807, 808, 809, 810, 905, 906, 1005, 1006    Tube-   105, 106, 107, 108, 205, 206, 207, 208, 711, 712, 713, 714, 803, 804    Adapter piece-   111, 112, 211, 212, 311, 312, 411, 511, 512, 611, 612, 715, 716,    717, 718, 719, 720, 811, 812, 813, 814, 815, 816 Web-   113, 114, 213, 214, 313, 314, 413, 513, 514, 613, 614 Wall facing    tubular heating body-   315, 316 Wall facing away from tubular heating body-   1017, 1417 Heat transport tube-   1100, 1200, 1300, 1400 Flow heater-   1101, 1201, 1401, 1401 a Hollow section-   1102, 1202, 1204, 1302, 1304, 1402, 1404 Tube-   1202 a, 1204 a, 1302 a, 1304 a Wall section of tube-   1103, 1203, 1303, 1403 Tubular heating body-   1104, 1105 Electric terminals-   901, 1001, 1301, 1305 Metal section-   1106, 1206, 1306 Powder or granular material-   1107, 1108, 1307, 1308 Front-side closing plate-   1207, 1208 Measuring or regulating element

1. A flow heater comprising: a metal section; a tube arrangement with atube interior space for passing through fluid to be heated, said tubearrangement being pressed into said metal section at least in somesections; and a tubular heating body arranged outside said tube interiorspace, said tubular heating body being at least one of mounted in andpressed into said metal section at least in some sections, said tubularheating body being surrounded, at least in some sections, by said tubearrangement for passing through fluid to be heated.
 2. A flow heater inaccordance with claim 1, wherein said metal section forms a hollowsection or comprises a component of a composite hollow section, in whichsaid tubular heating body and said tube arrangement are arranged andpressed in, at least in some sections, together with a sealing compound,in which at least one of said tubular heating body and said tubearrangement are embedded at least partly.
 3. A flow heater in accordancewith claim 1, wherein said metal section is a hollow section orcomprises a component of a composite hollow section, in which saidtubular heating body and said tube arrangement are arranged and pressedin, at least in some sections, together with a powder or granularmaterial, in which said tubular heating body and/or said tubearrangement are embedded at least partly.
 4. A flow heater in accordancewith claim 1, wherein said hollow section comprises two metal sectionsconnected to one another.
 5. A flow heater in accordance with claim 2,wherein: said tube arrangement has a wall section; and said hollowsection comprises a composite hollow section and said wall section formsa component of said composite hollow section and said metal sectionforms a component of said composite hollow section.
 6. A flow heater inaccordance with claim 5, wherein: said tube arrangement comprises atleast two tubes for passing fluid to be heated, each of sad tubes havinga wall section to provide wall sections; said composite hollow sectioncomprises another metal section to provide metal sections; saidcomposite hollow section is formed from said wall sections and saidmetal sections, which metal sections connect said wall sections of thetube arrangement to one another.
 7. A flow heater in accordance withclaim 2, wherein said tube arrangement comprises at least one tubedirectly in contact, at least in some sections, with said heating body.8. A flow heater in accordance with claim 3, wherein said metal sectionis formed of a material that has a lower thermal conductivity than saidpowder or granular material.
 9. A flow heater in accordance with claim3, further comprising a measuring and/or regulating element arranged onan outside of said metal section or embedded in said powder or granularmaterial or embedded in said metal section or embedded in a metal jacketof said tubular heating body.
 10. A flow heater in accordance with claim9, wherein said measuring and/or regulating element is connected inseries with a resistance wire winding of said tubular heating body. 11.A flow heater in accordance with claim 1, wherein said tube arrangementcomprises a tube having varying cross sections in contour including acrescent-shaped cross sectional portion and a round cross sectionalportion in said end area in the direction in which it extends.
 12. Aflow heater in accordance with claim 1, wherein said tube arrangementcomprises a tube that is pushed over said tubular heating body.
 13. Aflow heater in accordance with claim 1, wherein said metal sectioncomprises a tensioning mechanism for generating a pressure, which bringsabout a pressing of said tube arrangement into said metal section.
 14. Aflow heater in accordance with claim 1, wherein said metal sectioncomprises a solid body comprising at least one of a steel, an aluminumand a brass body, in which said tube arrangement and said tubularheating body are at least one of mounted and pressed.
 15. A flow heaterin accordance with claim 1, wherein said tube arrangement includes atube with a wall section which faces said tubular heating body and has ashape adapted to a section of a shape or geometry of a surface of saidtubular heating body.
 16. A flow heater in accordance with claim 1,wherein said tube arrangement includes a tube with a wall section whichfaces away from said tubular heating body and has a shape adapted to ashape or geometry of a surface of said metal section, which said surfaceof said metal section faces away from said tubular heating body.
 17. Aflow heater in accordance with claim 1, wherein said metal section hasat least one web, via which a surface of said metal section, which saidsurface faces away from said tubular heating body, is connected to saidtubular heating body.
 18. A flow heater in accordance with claim 1,wherein said tube arrangement comprises two tubes for passing throughfluid to be heated, said two tubes overlapping each other, in said atleast in some sections in which said tubular heating body is surrounded,viewed from said tubular heating body in a direction at right angles tothe direction in which said said tubular heating body extends.
 19. Aflow heater in accordance with claim 1, wherein: said tube arrangementcomprises a tube for passing through fluid to be heated; and said tubeencloses said tubular heating body.
 20. A flow heater in accordance withclaim 1, wherein: said tube arrangement comprises plural tubes forpassing through fluid to be heated; and at least one of said tubes isdirectly in contact with the surrounded said tubular heating body.
 21. Aflow heater in accordance with claim 1, further comprising a heattransport tube surrounding said tubular heating body wherein: said tubearrangement comprises plural tubes for passing through fluid to beheated; and at least one of said tubes is in contact with said heattransport tube.
 22. A flow heater in accordance with claim 21, whereinsaid heat transport tube is formed of a material with a higher thermalconductivity and/or a higher elasticity and/or a lower hardness and/or abetter deformability than a material of an outer metal jacket of saidtubular heating body.
 23. A flow heater in accordance with claim 14,wherein said tubular heating body is mounted in a hole in said metalsection.
 24. A flow heater in accordance with claim 1, wherein saidtubular heating body comprises unheated sections which come into directcontact with fluid to be heated, said unheated sections being notmounted in or not pressed into said metal section.
 25. A process formanufacturing a flow heater comprising the steps of: providing a metalsection, a tube arrangement with a tube interior space for passingthrough fluid to be heated and a tubular heating body arranged outsidethe tube interior space; and filling at least part of the interior spaceof the hollow section with a sealing compound, a powder or granularmaterial.